git/Documentation/pull-config.txt

pull.ff::
	By default, Git does not create an extra merge commit when merging
	a commit that is a descendant of the current commit. Instead, the
	tip of the current branch is fast-forwarded. When set to `false`,
	this variable tells Git to create an extra merge commit in such
	a case (equivalent to giving the `--no-ff` option from the command
	line). When set to `only`, only such fast-forward merges are
	allowed (equivalent to giving the `--ff-only` option from the
	command line). This setting overrides `merge.ff` when pulling.

pull.rebase::
	When true, rebase branches on top of the fetched branch, instead
	of merging the default branch from the default remote when "git
	pull" is run. See "branch.<name>.rebase" for setting this on a
	per-branch basis.
+
When `merges`, pass the `--rebase-merges` option to 'git rebase'
so that the local merge commits are included in the rebase (see
linkgit:git-rebase[1] for details).
+
When preserve, also pass `--preserve-merges` along to 'git rebase'
so that locally committed merge commits will not be flattened
by running 'git pull'.
+
When the value is `interactive`, the rebase is run in interactive mode.
+
*NOTE*: this is a possibly dangerous operation; do *not* use
it unless you understand the implications (see linkgit:git-rebase[1]
for details).

pull.octopus::
	The default merge strategy to use when pulling multiple branches
	at once.

pull.twohead::
	The default merge strategy to use when pulling a single branch.